It was in Jefferson's original draft. The other members of the committee wisely struck all that out of the document. Instead was left in a comment about the King's men provoking slave revolts, so it ended up with a mildly pro slavery statement in it.
But let us not underestimate the influence it had later on greatly expanding the abolition movement. Those five words "all men are created equal" exerted far more power on the subsequent direction of the country than the lament about the King's men fomenting slave rebellion.
I am convinced that Jefferson almost singlehandedly launched the abolition movement into the dominant force which it eventually became.
Had those words not been put in there, I think much of what happened in terms of abolition, would not have happened as it did.
I believe I know of one signer of the Declaration, that upon contemplating those words for time, eventually decided to free his own slaves.
But as I said, that wasn't the document's purpose when it was created, despite the fact that Lincoln made efforts to mislead people that it was with his "four score and seven years..." speech.
The thesis of the Declaration is that states have a right to be free, which is pretty ironic since Lincoln was commemorating an occasion in which the battle was won by the forces trying to subjugate a collection of states that wanted independence.
“I believe I know of one signer of the Declaration, that upon contemplating those words for time, eventually decided to free his own slaves.”
That was not Thomas Jefferson. He only freed 10 of the over 600 slaves he owned in his lifetime. Five while alive and five in his will after his death.